A set of golf clubs includes various types of clubs for use in different respective conditions or circumstances in which the ball must be hit during a golf game. An example set of clubs includes a “driver” for hitting the ball the longest distance on a course, several fairway “woods” for hitting the ball shorter distances than the driver, a set of irons (including one or more “wedges”) for hitting the ball a range of distances that are typically shorter than produced when hitting the ball using a wood, and at least one putter.
Irons and putters characteristically have a flat (planar) face, wherein the “face” or “striking face” is the surface that normally contacts the ball whenever the ball is being hit with the club. Irons have distinctively angled faces having for achieving lofts ranging from about 18 degrees to about 60 degrees. “Loft” is discussed later below.
A golf club comprises a head (also called a “clubhead”), a shaft affixed to the clubhead, and a grip affixed to the shaft. An exemplary head for an iron 10 is shown in FIG. 3, and includes a face 12, a sole 14, a toe 16, a heel 18, a back 20, a top line 22, and a hosel 24. The sole 14 usually is cambered or otherwise shaped to minimize friction if the clubhead should contact the ground during a swing. The hosel 24 receives the distal terminus of the shaft 26 of the golf club and is the means by which the head 10 is fastened to the shaft 26. The angle of the hosel 24 to the rest of the head 10 is the “lie” of the head 10. The face 12 of an iron typically is “offset,” wherein offset is a distance from the front-most part of the hosel 24 to the front-most part, or leading edge, of the head 10. The face 12 typically has a series of score lines (grooves) 28 extending substantially horizontally across the face 12. The particular depth and dimensions of the score lines 28 are regulated by United States Golf Association (USGA) rules because the score lines contribute to the launch conditions of a ball struck off the face 12.
“Loft” is a measurement, in degrees, of the angle at which the face 12 of the clubhead 10 lies relative to a perfectly vertical plane. In a typical set of irons from the “longest” iron to the “shortest” iron, the faces of the clubheads have progressively greater loft, which means that the faces are tilted progressively more from vertical. Loft affects the launch angle, backspin, and velocity of a struck ball. Striking a ball with a short iron will typically result in the ball having a higher launch angle and greater backspin compared to a ball struck with a long iron. Consequently, the trajectory of a ball struck with a short iron will typically be higher and shorter than the trajectory of a ball struck with a long iron. To aid the golfer, the irons are numbered to codify the loft; the higher the number, the greater the loft.
Hitting the ball at any location on the face 12 of an iron (or any golf club) does not yield the same result. Every club has a “sweet spot” (a zone located roughly in a central region of the face) that represents the best hitting zone on the face 12 for maximizing the probability of the golfer achieving the best and most predictable shot using the particular club. While executing a swing of the club, the golfer strives to hit the ball inside the sweet spot to provide the greatest probability that the ball will have the intended trajectory. Providing a clubhead with a larger sweet spot generally makes the clubhead more “forgiving” of a golfer's variability in swinging the club and striking a ball with it, thus providing the golfer with a greater assurance of making the intended shot.